refactor(root): relocate the contributing guide into .github/

.github/CONTRIBUTING.md

@@ -0,0 +1,68 @@
+# Contributing to bag-of-actions
+
+Thanks for your interest. This repository follows the Hyperpolymath
+estate standards defined in
+[hyperpolymath/standards](https://github.com/hyperpolymath/standards).
+
+## Licence
+
+This project is licensed under **MPL-2.0**. By contributing you agree
+that your contributions are licensed under the same terms. Every source
+file carries an `SPDX-License-Identifier` header; keep it when editing,
+and add one to any new file.
+
+## Development environment
+
+Use the toolchain declared by this repository (just zig).
+
+## Build and test
+
+This repo uses [`just`](https://just.systems) (the estate uses
+Justfiles, never Makefiles). Recipes available here:
+
+``` sh
+just            # list recipes
+just fmt        # format
+just fmt-check  # check formatting
+just lint       # lint
+just test-all   # run the full suite
+just doctor     # environment diagnostics
+```
+
+## Machine-readable artefacts
+
+This repo carries `.machine_readable/` A2ML files (`STATE.a2ml`,
+`META.a2ml`, `ECOSYSTEM.a2ml`, `AGENTIC.a2ml`, `NEUROSYM.a2ml`,
+`PLAYBOOK.a2ml`). If your change alters project state, architecture, or
+operational steps, update the corresponding file in the same PR — CI
+validates them.
+
+## Language policy
+
+The estate restricts which languages may be used. In particular Python,
+Go, TypeScript, AffineScript, V-lang, Java/Kotlin, Swift and Makefiles
+are **not** accepted in new code; AffineScript, Rust/SPARK, Zig, Deno,
+Gleam, Elixir, Haskell, Idris2, Agda, Julia and OCaml are. CI enforces
+this, so check the policy in `hyperpolymath/standards` before
+introducing a new language.
+
+## Documentation format
+
+Docs are AsciiDoc (`.adoc`) by default, including `README.adoc`. The
+GitHub-required community-health files stay Markdown: `SECURITY.md`,
+`CONTRIBUTING.md`, `CODE_OF_CONDUCT.md`, `CHANGELOG.md`. Do not add a
+`.md` duplicate of a doc that already exists as `.adoc`.
+
+## Pull requests
+
+1.  Branch from `main` — do not push to `main` directly; branch
+    protection requires review and passing checks.
+
+2.  Keep the change focused, and explain *why* in the PR body.
+
+3.  Make sure governance CI is green. It checks documentation presence,
+    packaging policy, secrets, licence consistency and workflow
+    security.
+
+4.  Security issues: follow `SECURITY.md` — report privately, never in a
+    public issue.

MAINTAINERS.adoc

@@ -62,4 +62,4 @@ For questions about project governance:
 
 * link:GOVERNANCE.adoc[Governance Model]
 * link:CODE_OF_CONDUCT.md[Code of Conduct]
-* link:CONTRIBUTING.adoc[Contributing Guide]
+* link:.github/CONTRIBUTING.md[Contributing Guide]